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                  <p class="p_Heading1"><span class="f_Heading1">Sequence Element Activations</span></p>



  
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                <p class="p_BodyText"><span class="f_BodyText">Sequence elements in a <a href="sequencediagram.htm">Sequence diagram</a> have </span><span class="f_BodyText" style="font-style: italic;">Activation rectangles</span><span class="f_BodyText"> drawn along their lifelines. These rectangles describe the time the element is active during the overall period of processing. This visual representation can be suppressed by right-clicking the Sequence diagram, and selecting the </span><span class="f_MenuKeyField">Suppress Activations</span><span class="f_BodyText"> menu option.</span></p>
<p class="p_BodyText"><span class="f_BodyText">In general, Enterprise Architect calculates the period of activation for you, but in some cases you might want to fine tune the rectangle length. There are several context menu options on a sequence message that you can use to accomplish this. To access the following context menu, right-click on the message and select the</span><span class="f_MenuKeyField"> Activations</span><span class="f_BodyText"> menu option.</span></p>
<p class="p_TextIndentedL2"><img src="seqactivations2.png" width="193" height="170" border="0" alt="SeqActivations2"></p>
<ul style="text-indent: 0px; margin-left: 30px; list-style-position: outside;">
<li><span class="f_MenuKeyField">Start New Message Group</span><span class="f_Bulletlist1">: S</span><span class="f_Bulletlist1">tarts off a new round of processing in the current diagram. This enables you to describe more than one processing scenario in a single diagram.</span></li>
<li><span class="f_MenuKeyField">Extend Source Activation Down</span><span class="f_Bulletlist1">: F</span><span class="f_Bulletlist1">orces an element to stay active beyond the normal processing period. This could be used to express an element that continues its own processing concurrently with other processes.</span></li>
<li><span class="f_MenuKeyField">Extend Source Activation Up</span><span class="f_Bulletlist1">: F</span><span class="f_Bulletlist1">orces an element's activation upwards.</span></li>
<li><span class="f_MenuKeyField">End Source Activation</span><span class="f_Bulletlist1">: T</span><span class="f_Bulletlist1">runcates the activation of the source element after the current message. This is useful for expressing an asynchronous message after which the source element becomes idle.</span></li>
<li><span class="f_MenuKeyField">End Target Activation</span><span class="f_Bulletlist1">:</span><span class="f_Bulletlist1"> Ends a Forced Activation started by the </span><span class="f_MenuKeyField">Extend Source Activation</span><span class="f_Bulletlist1"> options.</span></li>
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<p class="p_BodyText"><span class="f_BodyText">The </span><span class="f_MenuKeyField">Raise Activation Level</span><span class="f_BodyText"> and </span><span class="f_MenuKeyField">Lower Activation Level</span><span class="f_BodyText"> options display on the context menu only where their use is appropriate. For example, after a self-message the next message starts by default at a lower activation level but the </span><span class="f_MenuKeyField">Raise Activation Level</span><span class="f_BodyText"> command displays on the context menu to enable you to raise its level.</span></p>
<p class="p_BodyText"><span class="f_BodyText">A more convenient way to change activation levels is directly on the diagram. Whenever appropriate, left and/or right arrows display on specific connectors. In the following diagram, see connector 1.3. Click on the arrow to raise or lower the activation level.</span></p>
<p class="p_TextIndentedL2"><img src="sequence%20diagram%20activation%20arrows.png" width="362" height="301" border="0" alt="Sequence Diagram Activation Arrows"></p>
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<td valign="bottom" width="955" bgcolor="#efeff7" style="width:955px; background-color:#efeff7;"><p class="p_TiporNote" style="border-top: none; border-right: none; border-left: none;"><span class="f_TiporNote">Note:</span></p>
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<td width="955" bgcolor="#f7f7ff" style="width:955px; background-color:#f7f7ff;"><p class="p_TiporNoteText"><span class="f_TiporNoteText">Program flow can more accurately be depicted with nested activation levels for callback messages.</span></p>
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